In: Chemistry
Suppose we carry out the precipitation of Ag2GrO4(s) described in Example 4-10. If we obtain 2.058 g of precipitate, we might conclude that it is nearly pure Ag2GrO4(s), but if we obtain 2.112 g, we can be quite sure that the precipitate is not pure. Explain this difference.
The theoretical yield is 2.07 g 2 4 Ag CrO . If the mass actually obtained is less than this, it is likely that some of the pure material was not recovered, perhaps stuck to the walls of the flask in which the reaction occurred, or left suspended in the solution. Thus while it is almost a certainty that less than 2.07 g will be obtained, the absolute maximum mass of Ag2CrO4 expected is 2.07 g. If the precipitate weighs more than 2.07 g, the extra mass must be impurities (e.g., the precipitate was not thoroughly dried).
Actual yield likely less than theoretical due to loss during recovery; impurities possible if exceeding theoretical.